Apparatus for spreading material serving for the manufacture of fiberboards

ABSTRACT

Apparatus for spreading or scattering fiber or chip fleeces made up of a mixture of cuttings of extremely fine or superfine, fine, and coarser glue-covered chips for the subsequent press forming into fiberboards and the like. A mixture of chips is supplied to a fleece or particle carrier by gravity feed between sets of air emitting classifying registers. The upper portion of the classifying registers include oppositely facing air outlet openings which face the stream of chips and effect an initial classification by spreading some of the fine and superfine particles outwardly of the central stream. The lower part of the registers include openings facing oppositely to one another and away from the center line of the stream of particles and spaced from one another to permit passage therebetween of a central portion of the mixture without further modification. Baffle plates are also provided in preferred embodiments to assist in preventing further classification of the central stream in the lower regions of the registers. The baffle plates are vertically adjustable so as to accommodate varying conditions for desired varying thickness boards to be formed by the layers of particles passed through the distributing chamber containing the air classifying registers.

United States Patent [191 Beyer July 29, 1975 APPARATUS FOR SPREADING MATERIAL SERVING FOR THE MANUFACTURE OF FIBERBOARDS [75] Inventor: Reinhardt Beyer, Springe, Germany [73] Assignee: Bison-werke Bahre & Greten GmbH & Co. KG, Germany [22] Filed: Nov. 7, 1973 [21] Appl. No.: 413,424

[30] Foreign Application Priority Data Primary ExaminerRobert L. Spicer, Jr. Attorney, Agent, or Firm-Craig & Antonelli ABSTRACT Apparatus for spreading or scattering fiber or chip fleeces made up of a mixture of cuttings of extremely fine or superfine, fine, and coarser glue-covered chips for the subsequent press forming into fiberboards and the like. A mixture of chips is supplied to a fleece or particle carrier by gravity feed between sets of air emitting classifying registers. The upper portion of the classifying registers include oppositely facing air outlet openings which face the stream of chips and effect an initial classification by spreading some of the fine and superfine particles outwardly of the central stream. The lower part of the registers include openings facing oppositely to one another and away from the center line of the stream of particles and spaced from one another to permit passage therebetween of a central portion of the mixture without further modification. Baffie plates are also provided in preferred embodiments to assist in preventing further classification of the central stream in the lower regions of the registers. The baffle plates are vertically adjustable so as to accommodate varying conditions for desired varying thickness boards to be formed by the layers of particles passed through the distributing chamber containing the air classifying registers.

30 Claims, 4 Drawing Figures PATENTEI] JUL 2 9 I975 SHEET QQE APPARATUS FOR SPREADING MATERIAL SERVING FOR THE MANUFACTURE OF FIBERBOARDS BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to apparatus for the spreading or scattering of fiber or chip fleeces made up of a mixture of cuttings of extremely fine or superfine, fine, and coarser glue-covered chips for the subsequent press forming into fiberboards and the like. Preferred embodiments of this invention include a distributing chamber disposed above a fleece or particle carrier and of air register groups arranged in the distributing chamber. The register groups are mutually opposed to each other in mirror-image relationship at a distance from each other and are laterally offset with a gap in between. The mixture of cuttings is introduced from above in between these register groups. Air currents which are controllable in their velocity are fed to these register groups and exit from the register groups at opposite sides of a particle supply path in opposite directions.

Apparatus of the above-discussed general type have been disclosed in Austrian Pat. No. 243,496 and Swiss Pat. No. 402,398. The conventional devices of this kind have proven themselves well if fiberboards are to be produced with a relatively minor thickness of up to a thickness of about mm. In producing such thin fiberboards, the material introduced into the distributing chamber is placed, by the air currents having a screening effect, on a fleece carrier so that the two cover layers contain extremely fine and fine particles and the central layer contains coarser particles which, after the compression step, constitute an integral unit which is nonporous even in the central zone.

However, if it is intended to produce fiberboards having a thickness greater than 10 mm. with these prior arrangements, then there is the danger that too few fine particles are present in the central layer; i.e., the central layer becomes porous due to the high concentration of coarser particles. If the velocity of the screening air currents were to be reduced in order to avoid this disadvantage, the two cover layers would not contain sufficient fine components, which is likewise undesirable.

In order to overcome both of the above-discussed disadvantages, it has been contemplated to construct a device having several feeding points for the material to be spread. Between two register groups emitting screening air streams in opposite directions, a feed point would have to be arranged for material destined I for the central layer, and a homogeneous mixture of fine and coarser particles would have to be fed to this feed point. The last-mentioned feed point would be in addition to a feed point for the screened fine and superfine particles for the cover layers. However, such a construction is rather expensive and is justified only in case of plants having a very large daily output and correspondingly must operate with several spreading devices.

The present invention is based on solving the problem of manufacturing, by means of a single apparatus of the type mentioned in the foregoing, relatively thin fiberboards, as well as relatively thick fiberboards, so that the superficial or cover layers in case of each board thickness have a maximally uniform proportion of fime and extremely fine or cutting fibers, and so that furthermore, in case of relatively thick boards, a sufficient amount of fine particles is present in the central layer with the coarser particles i.e., the central zone of the finished fiberboards contains practically all other fine and coarser particles, except for the extremely fine components supplied to the cover layer, although, a homogeneous mixture of extremely fine, fine, and coarser particles is being introduced at a single feed point location where the material is fed for spreading purposes.

The present invention contemplates providing particle screening apparatus with upper regions of opposed register groups having outlet openings facing each other, and lower regions of opposed register groups having outlet openings facing away from each other with the outlet openings facing away from each other having such a mutual distance that a space remains therebetween where an unscreened portion of the mixture of cuttings can fall downwardly. Although the superfine particles and also a certain portion of the fine particles are air-classified or screened for the formation of the two cover layers by both the upper and lower regions of register groups, the screening process is practically eliminated for the other particles constituting the central layer which pass between the lower regions without further classification.

It is advantageous according to another feature of this invention to arrange at least two level-adjustable or vertically adjustable baffles in the space between the outlet openings. With these baffles, the quantity of the practically unscreened particles can be varied as these baffles act to limit effects of the air flow on the central stream of particles, as well as guide the flow of the central stream.

A preferred advantageous embodiment of the present invention includes a pair of transverse plates extending completely across the width of the distributing chamber at respective opposite sides of a centerplane through the path of particles to form a guide chute for the portion of particles not to be screened by the lower regions of register groups. Obliquely oriented baffles are provided between the registers of each register group and are displaceable with respect to portions of said respective transverse plates disposed in the same planes as said baffles.

If it is intended, for example, to produce first of all fiberboards having a relatively minor thickness, e.g., having a thickness of 8 mm., then the baffles provided between the registers of the two register groups are to be shifted downwardly onto the corresponding transverse plates, and the velocity of the screening air streams is to be selected, for example by increasing the number of revolutions of the blower or blowers associated therewith, so that a spreading effect is obtained which is similar to that obtained by the aforementioned conventional spreading device. The difference in operation as compared to the state of the art in this production of thin fiberboards resides in that the air velocities employed in the novel apparatus of this invention are higher than those of the conventional spreading devices.

If it is intended to manufacture relatively thick boards, for example those of a thickness of about 28 mm., then the baffles are pushed outwardly in the upward direction, and the speed of the air streams conducted through the registers is reduced. A portion of the fiber mixture fed from above to the register groups,

namely the superfine and fine particles, are fed to the two sides of the distributing chamber through the screening air currents from the registers. This fiber material which is screened into superfine and fine particles, enters, while traveling downwardly, into the effective zone of the air currents flowing out of the lower parts or regions of the registers in the traveling direction of the fibers (cuttings). Since the air currents flowing out of the lower parts of the registers are oriented obliquely downwardly, no damaging eddies occur in the lower zone of the registers. A portion of the fine components of the supplied mixture of cuttings, which has not been deflected sufficiently laterally in the upper region of the register groups, impinges on the baffles arranged between the registers of the two register groups, slides therealong downwardly in the direction toward the plane of symmetry of the register groups, and is here combined with fine and coarser particles which were practically not screened at all by the air currents. Thus, a central layer is formed consisting of fine and coarser particles, without the necessity for providing several feed points to spread the material.

It is preferred to form the registers of both register groups of ducts connected to the outlet openings of the registers so that the flow direction of the air streams can be controlled more effectively than in the case where the registers consist of boxes which are merely equipped with outlet apertures (see German Utility Model No. 7,037,391). The ducts terminating in the lower zone of the registers are preferably oriented obliquely downwardly toward the fleece carrier in a manner known per se (German Utility Model No. 7,037,391).

According to another feature of the invention, the transverse plates extending obliquely to the plane of symmetry of the register groups can each be provided with an extension piece, forming together a kind of guide chute for the fiber mixture of fine and coarser particles to be applied. Each extension piece is also preferably adjustable with respect to the transverse plate. A preferred advantageous embodiment of the invention includes two spiked rolls underneath the guide chute; the arrangement and structure of these rolls being explained below.

These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein:

FIG. 1 is a longitudinal sectional schematic view of a device for spreading a mixture of particles onto a particle carrier for subsequent pressforming into fiberboards and the like;

FIG. 2 is a sectional schematic view corresponding to a portion of FIG. 1 and illustrating apparatus constructed according to a preferred embodiment of the present invention;

FIG. 3 is a sectional schematic view similar to FIG. 2 and illustrating apparatus constructed according to another preferred embodiment of the present invention; and

FIG. 4 is a partial schematic view taken along the center plane of and at right angles to FIG. 3 and and showing the registers of a register group of the apparatus of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS The distributing chamber 1 can be moved, by means of rollers 2 running on rails 3, over or above a conveyor belt 4, on which belt 4 the particles fed from above into the distributing chamber 1 are placed in the form of a fleece. The particles first pass from a feeding means, not shown, into a container 5 arranged above a feeding belt 6, which latter is guided over a driven drum 7 and an idling drum 7'. The feeding belt 6 operates so that the particle mixture 8 is conducted toward the right. or in the direction toward the discharge end of the container 5. Rotary rakes 9, l0, and 11 are disposed at right angles to the traveling direction of the conveyor belt 4. These rakes 9, 10, ll rotate in the clockwise direction and throw the respectively uppermost stratum of the mixture 8 toward the left and away from the discharge end of the storage container 5. The rotary rakes 9, I0, and 11 are mounted on axles so that the depth of the bed formed by particles 8 at the discharge end of the container 5 is suitable for the introduction of the particles into the distrubuting chamber 1. The belts 4, 6 and rotary rakes 9, l0, 11 provided in the apparatus are driven by a motor, not shown.

The feeding belt 6 conducts, at its discharge end, the heterogeneous particle mixture into the effective zone of a spiked roll 12. The roll 12 is driven independently at a suitable speed. The spiked roll 12 cooperates with the feeding belt 6 so that a uniform and constant feeding of the particles in opened-up form to the distributing chamber 1 is obtained, and the discharge of adhering clumps of particles is prevented. The feeding device for the particles also comprises a pair of pivotable deflectors 13 arranged at a mutual spacing. These deflectors 13 are pivoted, via a linkage 14 by an eccentric drive 15 during the production of a fleece at a relatively high speed in a pendulating fashion, so that they execute, for example, 50 oscillations per minute, and the introduction of particles into the distributing chamber 1 is accomplished so that a uniform distrubtion is attained in the chamber. The spreading of the fleece on the conveyor belt takes place, in the apparatus illustrated in FIG. 1, during the movement of the distributing chamber in FIG. 1 in one direction, whereas during the return movement the feeding and distribution of the chips are interrupted. This does not mean that the distributing chamber must be moved to practice the invention. It is also contemplated to arrange the distributing chamber to be stationary, if the fleece carrier is moved.

Within the distributing chamber 1, two rows of air register groups 16, 17 are arranged transversely across the spreading width (perpendicular to the plane of FIG. 1) and at mutual distances. Each group 16, 17 includes several spaced-apart registers. Other preferred embodiments are contemplated without an interspace between the register groups. Both register groups are suspended at the upper wall of the distributing chamber 1 in a suitable manner. The vertical end faces of the individual registers are provided with a number of air outlet openings 18. The registers of the register group 16 are in communication with a distributing conduit 20 via an air feed pipe 19. The conduit 20 is connected with a housing 21 for a blower 22, taking in air through a conduit 23 from the right-hand end of the distributing chamber 1. Analogously, pipes 24 connect the upper ends of the register group 17 with a distributing conduit 25 associated'with a housing 26 for a blower 27, taking in air through a conduit 28 from the left-hand end of the distributing chamber 1. By means of valves 29 and 30, respectively, the air conveying conditions for each individual register can be set. Whereas the upper air conducting ducts 36 extend horizontally, the lower air conducting ducts 37 of both register groups are disposed to be inclined downwardly with respect to the horizontal, namely with increasing inclination the closer the air outlet openings of the ducts are to the fleece carrier 4.

According to the preferred embodiments of the in vention illustrated in FIGS. 2-4, the air register groups 16 and 17 of FIG. 1 are replaced by register groups 38 and 39, each of which consists of registers arranged at spacings to one another in a side-by-side relationship. The minimum spacing of these registers from one another corresponds to the width of one register in these embodiments. The registers of the two register groups 38, 39 have a different structure than the registers shown in FIG. 1. Each individual register group 38, 39 contains upper and lower groups or regions or ducts having a preferably rectangular cross section, to which air is fed via air feed pipes 19', 19" and 24, 24", respectively. The outlet openings 40 and 41 of group 42 and 43, respectively, of the ducts of the individual registers face the plane of symmetry 44 between the two register groups 38, 39 and blow air streams between adjacent registers of the opposed register group, so that glue-covered superfine and a portion of fine components falling from above are moved into opposite directions and classified. The other group 45 and 46, respectively, of ducts of each individual register terminates in outlet openings 47 and 48 disposed in the lower range of each individual register. The air streams emanating from openings 7 and 48 move in opposite directions away from the plane of symmetry 44. These air streams from openings 47 and 48 thus increase the classifying effect for the particles which are screened by the upwardly exiting air streams from openings 40 and 41. Thereby, an almost laminar flow is maintained in the two parts of the distrubuting chamber 1. The number of ducts or outlet openings 40 and 41 in the upper region and/or outlet openings 47 and 48 in the lower region of the registers of the registergroups which are provided depends on the respective requirement. In order to balance the relative air flow from the upper and 'lower regions, preferred embodiments include plates such as sheet metal plates for closing off respective ones of the upper outlet openings 40, 41 and lower outlet openings.

In the lower zone of the two register groups 38, 39, respectively baffles 49 and 50 are arranged respectively underneath the ducts 42 and 43 (FIG. 2). The width of these baffles 49, 50 corresponds to the width of each register group. The baffles 49, 50 are arranged to be at least vertically adjustable but can'also be pivotable and lockable in selectable pivotal positions according to other non-illustrated preferred embodiments. Also, preferred non-illustrated embodiments using multipartite baffles in place of the single baffles 49, 50 are contemplated. The objective attained by these baffles is that particles entering the space defined by the baffles are fed to the conveyor belt 4 ofthe central layer material without being further classified.

In the FIG. 3 embodiment, obliquelyv oriented baffles 51 and 52 are provided between the respective spacedapart adjacent registers of the two register groups. The

upper ends of these baffles 51, 52 are located approximately in the center of the height of the registers. and their lower ends rest on respective transverse plates 53 and 54. Plates 53, 54 extending over the entire width of the register groups and are arranged in the lower zone so that they form a slot 55 which is extended in the downward direction by feeding surfaces 56 and 57.

The baffles 51 and 52 are preferably guided with respect to either the registers between which they are located or by the transverse plates 53 and 54. The baffles 51, 52 are arranged to be displaceable and/or adjustable in order to place them into optimum vertical positions corresponding to the thickness of board to be manufactured from the mixture supplied to carrier 4.

Extension pieces 58 and 59, respectively. can be arranged at each of the respective baffles 51 and 52. An adjustable mounting is also preferable for these extensions, permitting particularly a pivoting and locking in a selected position. The guide surfaces 56, 57 can also be constructed to be pivotable and adjustable; and lockable into position, especially in a releasable arrangement, with respect to other points of the system. The dash line extensions of plates 53 and 54 indicate that these plates can be adjustably displaced outwardly in the upward direction in order to change the size of chute or funnel 60.

If it is necessary to take care of making the material fed to the conveyor belt 4 via the chute 60 of a uniform consistency, it is advantageous according to another feature of the FIG. 3 embodiment to arrange two spiked rolls 61 and 62 below the chute formed by baffles 51, 52 and transverse plates 53, 54. The length of rolls 6], 62 corresponds approximately to the width of the register groups. These spiked rolls or the like are to be driven not only so that they move the particles fed thereto toward the outside (as indicated by arrows in FIG. 3), but also the spiked rolls should also execute reciprocating motions at right angles to the fleece carrier 4, in order to effect a uniform distribution of the material fed to the fleece carrier. During operation with the spiked rolls, roll 61 rotates clockwise and roll 62 counterclockwise for conveying the material between the rolls while mixing same. The spacing between rolls 61 and 62 is also adjustable.

The spiked rolls 6], 62 which can be reciprocated oscillatingly in the direction of their axes of rotation can also be replaced by other means, for example by a plurality of hinged flaps, similar to the hinged flaps 13, but with pivoting axes extending in parallel to the traveling direction of the fleece carrier or the spreading station.

An example of the composition of the particle mixture to be classified by the present invention is as follows:

8-15 percent superfine particles passes through mesh width of 0.315 mm. 8-15 percent fine particles passes through mesh width of 1 mm.

84-70 percent middle fine and coarser particles I mesh width greater than 1 mm.

The proportion of material which is passed through the lower group of registers without further classification can be controlled with the apparatus of the present invention to suit the particular board width and composition to be manufactured by appropriate control of the air flow in the upper and lower registers, the spacing of the registers from the centerline of the particle flow path, and the adjustment of baffles 49, 50, 51, 52 and plates 53, 54.

While l have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to a person skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are obvious to one of ordinary skill in the art.

What I claim is:

1. Apparatus for spreading a mixture of superfine, fine and coarser particles onto a particle carrier for subsequent press-forming into fiberboards and the like; said apparatus comprising:

particle supply means spaced vertically from said particle carrier and including means for supplying a heterogeneous mixture of superfine, fine and coarser particles to said particle carrier such that said mixture falls downwardly towards said particle carrier with a particle path centerline extending downwardly from said particle supply means to said particle carrier;

upper particle classifying means disposed between said particle supply means and said particle carrier and including a plurality of upper conduit means at each of opposite lateral sides of the path centerline, the upper conduit means at one side of the path centerline having upper outlet openings which face corresponding upper outlet openings of the upper conduit means at the other side of the path centerline, said upper outlet openings being spaced from one another in a direction transverse to said path centerline to permit passage therebetween of portions of said mixture while gas under pressure is discharged from said upper outlet openings to effect a classification of the particles with the superfine and fine particles spaced further from the path centerline than the coarser particles;

lower particle classifying means disposed between said upper particle classifying means and said particle carrier and including a plurality of lower conduit means at each of said opposite lateral sides of the path centerline, the lower conduit means at one side of the path centerline having lower outlet openings facing in one direction away from the path centerline and the lower conduit means at the other side of the path centerline having lower out let openings facing in an opposite direction away from the path centerline, said lower outlet openings at the one side of said centerline path being spaced from the lower outlet openings at the other side of the centerline path to form a space therebetween for the passage therethrough of a portion of the particle mixture without further classification by said lower particle classifying means while other portions of the particle mixture pass outwardly of said lower outlet openings and are further classified by gas under pressure exiting from said lower outlet openings, whereby boards can be constructed with that portion of the particle mixture which is classified only by the upper classifying means forming central board sections and that portion of the particle mixture which is classified by both the upper and lower classifying means forming edge board sections.

2. Apparatus according to claim 1, wherein said gas under pressure is air, and wherein separate means are provided for controlling the velocity of the air exiting from the respective upper and lower outlet openings.

3. Apparatus according to claim 1, wherein said upper conduit means are arranged in vertical rows immediately adjacent one another, said vertical rows being spaced from one another in a direction extending transverse to said particle carrier for permitting flow of gas across from said upper outlet openings.

4. Apparatus according to claim 3, wherein said lower conduit means are arranged in vertical rows immediately adjacent one another which are aligned with respective vertical rows of said upper conduit means.

5. Apparatus according to claim 3, wherein said gas under pressure is air, and wherein separate means are provided for controlling the velocity of the air exiting from the respective upper and lower outlet openings.

6. Apparatus according to claim 1, wherein baffle means are disposed at respective opposite sides of the space formed between the lower outlet openings for adjusting the flow of gas in said space and for guiding that portion of said particle mixture passing through said space.

7. Apparatus according to claim 6, wherein said baffle means include vertically adjustable baffle plates at each of the respective opposite sides of said space.

8. Apparatus according to claim 6, further comprising a distributing chamber for housing said classifying means, wherein said upper and lower outlet openings are substantially uniformly distributed across the width of said distributing chamber with said outlet openings arranged in a mirror image-relationship at opposite sides of a centerplane through which said path centerline extends.

9. Apparatus according to claim 8, wherein said baffle means includes a pair of transverse plates extending across the width of said distributing chambers at respective opposite sides of said centerplane, baffle plates arranged respectively in substantially the same planes as said transverse plates, and means for accommodating displacement of said baffle plates with respect to the associated transverse plates.

10. Apparatus according to claim 9, wherein said transverse plates and baffle plates extend in oblique planes with respect to said centerplane.

11. Apparatus according to claim 10, wherein said transverse plates extend below said baffle plates.

12. Apparatus according to claim 11, wherein said baffle plates extend between respective vertical rows of said lower conduit means.

13. Apparatus according to claim 12, further comprising a pair of driven and reciprocated spiked rolls positioned below a chute formed by said transverse plates for assisting in uniformly spreading that portion of the particle mixture passing between said lower outlet openings.

14. Apparatus according to claim 1, wherein said mixture consists of superfine, fine and coarser gluecovered chips for the subsequent formation of fiberboards.

15. Apparatus according to claim 1, wheren said conduit means includes register groups having ducts connecting the source of pressurized gas to each of respective ones of said outlet openings.

16. Apparatus according to claim 5. wherein said conduit means includes register groups having ducts connecting a source of pressurized air to each of respective ones of said outlet openings.

17. Apparatus according to claim 15, wherein the ducts connected with said lower outlet openings are oriented obliquely downwardly toward said particle carrier in a direction away from said particle path centerline.

:18. Apparatus according to claim l7, wherein said particle carrier is a conveyor belt.

19. Apparatus according to claim 6, wherein said baffle means includes baffle plates and extension pieces connected at the lower ends of said baffle plates, said extension pieces forming a guide chute for directing that portion of said particle mixture passing through said space onto said particle carrier.

20. Apparatus according to claim 19, wherein each of said extension pieces are adjustable with respect to respective ones of said baffle plates connected thereto.

21. Apparatus according to claim 20, further comprising a distributing chamber for housing said classifying means, wherein said upper and lower outlet openings are substantially uniformly distributed across the width of said distributing chamber with said outlet openings arranged in a mirror image-relationship at opposite sides of a centerplane through which said path centerline extends.

22. Apparatus according to claim 19, further comprising a pair of driven and reciprocated spiked rolls positioned below a chute formed by said transverse plates for assisting in uniformly spreading that portion of the particle mixture passing between said lower outlet openings.

23. Apparatus according to claim 22, wherein said spiked rolls are disposed at right angles to the direction of motion of said particle carrier, and wherein roll driving means are provided for rotating said spiked rolls in opposite directions of rotation with respect to one another.

24. Apparatus according to claim 23, wherein said roll driving means includes means for rotating said spiked rolls such that, as viewed in the direction of the axes of rotation of said spiked rolls, the left most spiked roll rotates counterclockwise and the right most spiked roll rotates clockwise, with a consequent outward dispersion of said particles with respect to said particle path centerline.

25. Apparatus for spreading a mixture of particles onto a particle carrier for subsequent press-forming into fiberboards and the like; said apparatus comprising:

particle supply means spaced vertically from said particle carrier and including means for supplying a mixture of particles to said particle carrier such that said mixture falls downwardly towards said particle carrier with a particle path centerline extending downwardly from said particle supply means to said particle carrier;

upper particle classifying means disposed between said particle supply means and said particle carrier and including at least one upper conduit means at each of opposite lateral sides of the path centerline, the upper conduit means at one side of the path centerline having at least one upper outlet opening which faces a corresponding at least one upper outlet opening of the upper conduit means at the other side of the path centerline, said upper outlet openings being spaced from one another in a direction transverse to said path centerline to permit passage thereby of portions of said mixture while gas under pressure is discharged from said upper outlet openings to effect a classification of the particles with the finer particles spaced further from the path centerline than the coarser particles;

lower particle classifying means disposed between said upper particle classifying means and said particle carrier and including at least one lower conduit means at each of said opposite lateral sides of the path centerline, the lower conduit means at one side of the path centerline having at least one lower outlet opening facing in one direction away from the path centerline and the lower conduit means at the other side of the path centerline having at least one lower outlet opening'facing in an opposite direction away from the path centerline, said at least one lower outlet opening at the one side of said centerline path being spaced from the at least one lower outlet opening at the other side of the centerline path to form a space therebetween for the passage therethrough of a portion of the particle mixture without further classification by said lower particle classifying means while other portions of the particle mixture pass outwardly of said lower outlet openings and are further classified by gas under pressure exiting from said lower outlet openings, whereby boards can be constructed with that portion of the particle mixture which is classified only by the upper classifying means forming central board sections and that portion of the particle mixture which is classified by both the upper and lower classifying means forming edge board sections.

26. Apparatus according to claim 25, wherein said gas under pressure is air, and wherein separate means are provided for controlling the velocity of the air exiting from the respective upper and lower outlet openings.

27. Apparatus according to claim 25, wherein baffle means are disposed at respective opposite sides of the space formed between the lower outlet openings for adjusting the flow of gas in said space and for guiding that portion of said particle mixture passing through said space.

28. Apparatus according to claim 25, wherein said mixture consists of superfine, fine and coarser gluecovered chips for the subsequent formation of fiberboards.

29. Apparatus according to claim 25, wherein said conduit means includes register groups having ducts connecting the source of pressurized gas to each of respective ones of said outlet openings.

30. Apparatus according to claim 29, wherein the ducts connected with said lower outlet openings are oriented obliquely downwardly toward said particle carrier in a direction away from said particle path centerline. 

1. Apparatus for spreading a mixture of superfine, fine and coarser particles onto a particle carrier for subsequent pressforming into fiberboards and the like; said apparatus comprising: particle supply means spaced vertically from said particle carrier and including means for supplying a heterogeneous mixture of superfine, fine and coarser particles to said particle carrier such that said mixture falls downwardly towards said particle carrier with a particle path centerline extending downwardly from said particle supply means to said particle carrier; upper particle classifying means disposed between said particle supply means and said particle carrier and including a plurality of upper conduit means at each of opposite lateral sides of the path centerline, the upper conduit means at one side of the path centerline having upper outlet openings which face correspOnding upper outlet openings of the upper conduit means at the other side of the path centerline, said upper outlet openings being spaced from one another in a direction transverse to said path centerline to permit passage therebetween of portions of said mixture while gas under pressure is discharged from said upper outlet openings to effect a classification of the particles with the superfine and fine particles spaced further from the path centerline than the coarser particles; lower particle classifying means disposed between said upper particle classifying means and said particle carrier and including a plurality of lower conduit means at each of said opposite lateral sides of the path centerline, the lower conduit means at one side of the path centerline having lower outlet openings facing in one direction away from the path centerline and the lower conduit means at the other side of the path centerline having lower outlet openings facing in an opposite direction away from the path centerline, said lower outlet openings at the one side of said centerline path being spaced from the lower outlet openings at the other side of the centerline path to form a space therebetween for the passage therethrough of a portion of the particle mixture without further classification by said lower particle classifying means while other portions of the particle mixture pass outwardly of said lower outlet openings and are further classified by gas under pressure exiting from said lower outlet openings, whereby boards can be constructed with that portion of the particle mixture which is classified only by the upper classifying means forming central board sections and that portion of the particle mixture which is classified by both the upper and lower classifying means forming edge board sections.
 2. Apparatus according to claim 1, wherein said gas under pressure is air, and wherein separate means are provided for controlling the velocity of the air exiting from the respective upper and lower outlet openings.
 3. Apparatus according to claim 1, wherein said upper conduit means are arranged in vertical rows immediately adjacent one another, said vertical rows being spaced from one another in a direction extending transverse to said particle carrier for permitting flow of gas across from said upper outlet openings.
 4. Apparatus according to claim 3, wherein said lower conduit means are arranged in vertical rows immediately adjacent one another which are aligned with respective vertical rows of said upper conduit means.
 5. Apparatus according to claim 3, wherein said gas under pressure is air, and wherein separate means are provided for controlling the velocity of the air exiting from the respective upper and lower outlet openings.
 6. Apparatus according to claim 1, wherein baffle means are disposed at respective opposite sides of the space formed between the lower outlet openings for adjusting the flow of gas in said space and for guiding that portion of said particle mixture passing through said space.
 7. Apparatus according to claim 6, wherein said baffle means include vertically adjustable baffle plates at each of the respective opposite sides of said space.
 8. Apparatus according to claim 6, further comprising a distributing chamber for housing said classifying means, wherein said upper and lower outlet openings are substantially uniformly distributed across the width of said distributing chamber with said outlet openings arranged in a mirror image-relationship at opposite sides of a centerplane through which said path centerline extends.
 9. Apparatus according to claim 8, wherein said baffle means includes a pair of transverse plates extending across the width of said distributing chambers at respective opposite sides of said centerplane, baffle plates arranged respectively in substantially the same planes as said transverse plates, and means for accommodating displacement of said baffle plates with respect to the associated transverse plates.
 10. ApparAtus according to claim 9, wherein said transverse plates and baffle plates extend in oblique planes with respect to said centerplane.
 11. Apparatus according to claim 10, wherein said transverse plates extend below said baffle plates.
 12. Apparatus according to claim 11, wherein said baffle plates extend between respective vertical rows of said lower conduit means.
 13. Apparatus according to claim 12, further comprising a pair of driven and reciprocated spiked rolls positioned below a chute formed by said transverse plates for assisting in uniformly spreading that portion of the particle mixture passing between said lower outlet openings.
 14. Apparatus according to claim 1, wherein said mixture consists of superfine, fine and coarser glue-covered chips for the subsequent formation of fiberboards.
 15. Apparatus according to claim 1, wheren said conduit means includes register groups having ducts connecting the source of pressurized gas to each of respective ones of said outlet openings.
 16. Apparatus according to claim 5, wherein said conduit means includes register groups having ducts connecting a source of pressurized air to each of respective ones of said outlet openings.
 17. Apparatus according to claim 15, wherein the ducts connected with said lower outlet openings are oriented obliquely downwardly toward said particle carrier in a direction away from said particle path centerline.
 18. Apparatus according to claim 17, wherein said particle carrier is a conveyor belt.
 19. Apparatus according to claim 6, wherein said baffle means includes baffle plates and extension pieces connected at the lower ends of said baffle plates, said extension pieces forming a guide chute for directing that portion of said particle mixture passing through said space onto said particle carrier.
 20. Apparatus according to claim 19, wherein each of said extension pieces are adjustable with respect to respective ones of said baffle plates connected thereto.
 21. Apparatus according to claim 20, further comprising a distributing chamber for housing said classifying means, wherein said upper and lower outlet openings are substantially uniformly distributed across the width of said distributing chamber with said outlet openings arranged in a mirror image-relationship at opposite sides of a centerplane through which said path centerline extends.
 22. Apparatus according to claim 19, further comprising a pair of driven and reciprocated spiked rolls positioned below a chute formed by said transverse plates for assisting in uniformly spreading that portion of the particle mixture passing between said lower outlet openings.
 23. Apparatus according to claim 22, wherein said spiked rolls are disposed at right angles to the direction of motion of said particle carrier, and wherein roll driving means are provided for rotating said spiked rolls in opposite directions of rotation with respect to one another.
 24. Apparatus according to claim 23, wherein said roll driving means includes means for rotating said spiked rolls such that, as viewed in the direction of the axes of rotation of said spiked rolls, the left most spiked roll rotates counterclockwise and the right most spiked roll rotates clockwise, with a consequent outward dispersion of said particles with respect to said particle path centerline.
 25. Apparatus for spreading a mixture of particles onto a particle carrier for subsequent press-forming into fiberboards and the like; said apparatus comprising: particle supply means spaced vertically from said particle carrier and including means for supplying a mixture of particles to said particle carrier such that said mixture falls downwardly towards said particle carrier with a particle path centerline extending downwardly from said particle supply means to said particle carrier; upper particle classifying means disposed between said particle supply means and said particle carrier and including at least one upper conduit means at each of oppOsite lateral sides of the path centerline, the upper conduit means at one side of the path centerline having at least one upper outlet opening which faces a corresponding at least one upper outlet opening of the upper conduit means at the other side of the path centerline, said upper outlet openings being spaced from one another in a direction transverse to said path centerline to permit passage thereby of portions of said mixture while gas under pressure is discharged from said upper outlet openings to effect a classification of the particles with the finer particles spaced further from the path centerline than the coarser particles; lower particle classifying means disposed between said upper particle classifying means and said particle carrier and including at least one lower conduit means at each of said opposite lateral sides of the path centerline, the lower conduit means at one side of the path centerline having at least one lower outlet opening facing in one direction away from the path centerline and the lower conduit means at the other side of the path centerline having at least one lower outlet opening facing in an opposite direction away from the path centerline, said at least one lower outlet opening at the one side of said centerline path being spaced from the at least one lower outlet opening at the other side of the centerline path to form a space therebetween for the passage therethrough of a portion of the particle mixture without further classification by said lower particle classifying means while other portions of the particle mixture pass outwardly of said lower outlet openings and are further classified by gas under pressure exiting from said lower outlet openings, whereby boards can be constructed with that portion of the particle mixture which is classified only by the upper classifying means forming central board sections and that portion of the particle mixture which is classified by both the upper and lower classifying means forming edge board sections.
 26. Apparatus according to claim 25, wherein said gas under pressure is air, and wherein separate means are provided for controlling the velocity of the air exiting from the respective upper and lower outlet openings.
 27. Apparatus according to claim 25, wherein baffle means are disposed at respective opposite sides of the space formed between the lower outlet openings for adjusting the flow of gas in said space and for guiding that portion of said particle mixture passing through said space.
 28. Apparatus according to claim 25, wherein said mixture consists of superfine, fine and coarser glue-covered chips for the subsequent formation of fiberboards.
 29. Apparatus according to claim 25, wherein said conduit means includes register groups having ducts connecting the source of pressurized gas to each of respective ones of said outlet openings.
 30. Apparatus according to claim 29, wherein the ducts connected with said lower outlet openings are oriented obliquely downwardly toward said particle carrier in a direction away from said particle path centerline. 